Guess touch draw mode on the browser by default

So that phone users don't have to dig through the preferences to enable
touch drawing. We now guess if the user wants to draw via touch by
having received a tablet event or not. Touch drawing is the default, the
first tablet event will switch it over to pan instead. The user can
still explicitly specify what they want in the preferences.

src/desktop/dialogs/settingsdialog/input.cpp

@@ -140,13 +140,12 @@ void Input::initTablet(
 	auto *oneTouch = utils::addRadioGroup(
 		form, tr("One-finger input:"), true,
 		{
-			{tr("Do nothing"), 0},
-			{tr("Draw"), 1},
-			{tr("Pan canvas"), 2},
+			{tr("None"), int(desktop::settings::OneFingerTouchAction::Nothing)},
+			{tr("Draw"), int(desktop::settings::OneFingerTouchAction::Draw)},
+			{tr("Pan"), int(desktop::settings::OneFingerTouchAction::Pan)},
+			{tr("Guess"), int(desktop::settings::OneFingerTouchAction::Guess)},
 		});
-	oneTouch->button(0)->setChecked(true);
-	settings.bindOneFingerDraw(oneTouch->button(1));
-	settings.bindOneFingerScroll(oneTouch->button(2));
+	settings.bindOneFingerTouch(oneTouch);
 	settings.bindTouchGestures(oneTouch->button(1), &QWidget::setDisabled);
 
 	auto *twoTouch = new utils::EncapsulatedLayout;

src/desktop/dialogs/systeminfodialog.cpp

@@ -175,10 +175,10 @@ QString SystemInfoDialog::getSystemInfo() const
 	info += QStringLiteral("Global smoothing: %1\n").arg(settings.smoothing());
 	info += QStringLiteral("Global pressure curve: \"%1\"\n")
 				.arg(settings.globalPressureCurve());
-	info += QStringLiteral("One-finger draw: %1\n")
-				.arg(boolToYesNo(settings.oneFingerDraw()));
-	info += QStringLiteral("One-finger scroll: %1\n")
-				.arg(boolToYesNo(settings.oneFingerScroll()));
+	info +=
+		QStringLiteral("One-finger touch action: %1\n")
+			.arg(QMetaEnum::fromType<desktop::settings::OneFingerTouchAction>()
+					 .valueToKey(settings.oneFingerTouch()));
 	info += QStringLiteral("Two-finger zoom: %1\n")
 				.arg(boolToYesNo(settings.twoFingerZoom()));
 	info += QStringLiteral("Two-finger rotate: %1\n")

src/desktop/main.cpp

@@ -827,10 +827,11 @@ static StartupOptions initApp(DrawpileApp &app)
 		// We'll flush the flag that we checked the input here in case we crash.
 		settings.setAndroidStylusChecked(true);
 		settings.trySubmit();
-		// Enable fingerpainting if this device doesn't have a stylus.
+		// Disable finerpainting if this device is detected to have a stylus.
 		bool hasStylus = utils::androidHasStylusInput();
-		settings.setOneFingerScroll(hasStylus);
-		settings.setOneFingerDraw(!hasStylus);
+		settings.setOneFingerTouch(
+			int(hasStylus ? desktop::settings::OneFingerTouchAction::Draw
+						  : desktop::settings::OneFingerTouchAction::Guess));
 	}
 
 	settings.bindCaptureVolumeRocker([](bool capture) {

src/desktop/mainwindow.cpp

@@ -2256,8 +2256,7 @@ void MainWindow::toggleTabletEventLog()
 				const desktop::settings::Settings &settings = dpApp().settings();
 				DP_event_log_write_meta("Tablet enabled: %d", settings.tabletEvents());
 				DP_event_log_write_meta("Tablet eraser action: %d", settings.tabletEraserAction());
-				DP_event_log_write_meta("One-finger draw: %d", settings.oneFingerDraw());
-				DP_event_log_write_meta("One-finger scroll: %d", settings.oneFingerScroll());
+				DP_event_log_write_meta("One-finger touch action: %d", settings.oneFingerTouch());
 				DP_event_log_write_meta("Two-finger rotate: %d", settings.twoFingerRotate());
 				DP_event_log_write_meta("Two-finger zoom: %d", settings.twoFingerZoom());
 				DP_event_log_write_meta("Gestures: %d", settings.touchGestures());

src/desktop/scene/canvasview.cpp

@@ -66,13 +66,13 @@ CanvasView::CanvasView(QWidget *parent)
 	, m_saveInProgress(false)
 	, m_pointertracking(false)
 	, m_pixelgrid(true)
-	, m_enableTouchScroll(true)
-	, m_enableTouchDraw(false)
 	, m_enableTouchPinch(true)
 	, m_enableTouchTwist(true)
 	, m_useGestureEvents(false)
 	, m_touching(false)
 	, m_touchRotating(false)
+	, m_anyTabletEventsReceived(false)
+	, m_oneFingerTouchAction(int(ONE_FINGER_TOUCH_DEFAULT))
 	, m_touchMode(TouchMode::Unknown)
 	, m_dpi(96)
 	, m_brushCursorStyle(int(view::Cursor::TriangleRight))
@@ -131,8 +131,8 @@ CanvasView::CanvasView(QWidget *parent)
 	}
 
 	settings.bindTabletEvents(this, &widgets::CanvasView::setTabletEnabled);
-	settings.bindOneFingerDraw(this, &widgets::CanvasView::setTouchDraw);
-	settings.bindOneFingerScroll(this, &widgets::CanvasView::setTouchScroll);
+	settings.bindOneFingerTouch(
+		this, &widgets::CanvasView::setOneFingerTouchAction);
 	settings.bindTwoFingerZoom(this, &widgets::CanvasView::setTouchPinch);
 	settings.bindTwoFingerRotate(this, &widgets::CanvasView::setTouchTwist);
 	settings.bindTouchGestures(
@@ -171,6 +171,21 @@ CanvasView::CanvasView(QWidget *parent)
 		this, &CanvasView::setShowTransformNotices);
 }
 
+void CanvasView::setOneFingerTouchAction(int oneFingerTouchAction)
+{
+	switch(oneFingerTouchAction) {
+	case int(desktop::settings::OneFingerTouchAction::Nothing):
+	case int(desktop::settings::OneFingerTouchAction::Draw):
+	case int(desktop::settings::OneFingerTouchAction::Pan):
+	case int(desktop::settings::OneFingerTouchAction::Guess):
+		m_oneFingerTouchAction = oneFingerTouchAction;
+		break;
+	default:
+		qWarning("Unknown one finger touch action %d", oneFingerTouchAction);
+		break;
+	}
+}
+
 void CanvasView::setTouchUseGestureEvents(bool useGestureEvents)
 {
 	if(useGestureEvents && !m_useGestureEvents) {
@@ -894,6 +909,42 @@ void CanvasView::clearKeys()
 	resetCursor();
 }
 
+bool CanvasView::isTouchDrawEnabled() const
+{
+	switch(m_oneFingerTouchAction) {
+	case int(desktop::settings::OneFingerTouchAction::Draw):
+		return true;
+	case int(desktop::settings::OneFingerTouchAction::Guess):
+		return !m_anyTabletEventsReceived;
+	default:
+		return false;
+	}
+}
+
+bool CanvasView::isTouchPanEnabled() const
+{
+	switch(m_oneFingerTouchAction) {
+	case int(desktop::settings::OneFingerTouchAction::Pan):
+		return false;
+	case int(desktop::settings::OneFingerTouchAction::Guess):
+		return m_anyTabletEventsReceived;
+	default:
+		return false;
+	}
+}
+
+bool CanvasView::isTouchDrawOrPanEnabled() const
+{
+	switch(m_oneFingerTouchAction) {
+	case int(desktop::settings::OneFingerTouchAction::Pan):
+	case int(desktop::settings::OneFingerTouchAction::Draw):
+	case int(desktop::settings::OneFingerTouchAction::Guess):
+		return true;
+	default:
+		return false;
+	}
+}
+
 canvas::Point CanvasView::mapToCanvas(
 	long long timeMsec, const QPoint &point, qreal pressure, qreal xtilt,
 	qreal ytilt, qreal rotation) const
@@ -1370,7 +1421,7 @@ void CanvasView::gestureEvent(QGestureEvent *event)
 			[[fallthrough]];
 		case Qt::GestureUpdated:
 		case Qt::GestureFinished:
-			if((m_enableTouchScroll || m_enableTouchDraw) &&
+			if(isTouchDrawOrPanEnabled() &&
 			   cf.testFlag(QPinchGesture::CenterPointChanged)) {
 				QPointF d = pinch->centerPoint() - pinch->lastCenterPoint();
 				horizontalScrollBar()->setValue(
@@ -1420,7 +1471,7 @@ void CanvasView::gestureEvent(QGestureEvent *event)
 			[[fallthrough]];
 		case Qt::GestureUpdated:
 		case Qt::GestureFinished:
-			if(!hadPinchUpdate && (m_enableTouchScroll || m_enableTouchDraw)) {
+			if(!hadPinchUpdate && isTouchDrawOrPanEnabled()) {
 				horizontalScrollBar()->setValue(
 					horizontalScrollBar()->value() - delta.x());
 				verticalScrollBar()->setValue(
@@ -1777,7 +1828,7 @@ void CanvasView::touchEvent(QTouchEvent *event)
 
 		m_touchDrawBuffer.clear();
 		m_touchRotating = false;
-		if(m_enableTouchDraw && pointsCount == 1 &&
+		if(isTouchDrawEnabled() && pointsCount == 1 &&
 		   !compat::isTouchPad(event)) {
 			DP_EVENT_LOG(
 				"touch_draw_begin x=%f y=%f pendown=%d touching=%d type=%d "
@@ -1787,7 +1838,7 @@ void CanvasView::touchEvent(QTouchEvent *event)
 				qUtf8Printable(compat::touchDeviceName(event)),
 				qUtf8Printable(compat::debug(points)),
 				qulonglong(event->timestamp()));
-			if(m_enableTouchScroll || m_enableTouchPinch ||
+			if(isTouchPanEnabled() || m_enableTouchPinch ||
 			   m_enableTouchTwist) {
 				// Buffer the touch first, since it might end up being the
 				// beginning of an action that involves multiple fingers.
@@ -1815,7 +1866,7 @@ void CanvasView::touchEvent(QTouchEvent *event)
 	}
 
 	case QEvent::TouchUpdate:
-		if(m_enableTouchDraw &&
+		if(isTouchDrawEnabled() &&
 		   ((pointsCount == 1 && m_touchMode == TouchMode::Unknown) ||
 			m_touchMode == TouchMode::Drawing) &&
 		   !compat::isTouchPad(event)) {
@@ -1892,7 +1943,7 @@ void CanvasView::touchEvent(QTouchEvent *event)
 			bool havePinchOrTwist =
 				haveMultiTouch && (m_enableTouchPinch || m_enableTouchTwist);
 			bool havePan = havePinchOrTwist ||
-						   ((m_enableTouchScroll || m_enableTouchDraw) &&
+						   (isTouchDrawOrPanEnabled() &&
 							(haveMultiTouch || !compat::isTouchPad(event)));
 			if(havePan) {
 				m_touching = true;
@@ -1960,9 +2011,9 @@ void CanvasView::touchEvent(QTouchEvent *event)
 
 	case QEvent::TouchEnd:
 	case QEvent::TouchCancel:
-		if(m_enableTouchDraw && ((m_touchMode == TouchMode::Unknown &&
-								  !m_touchDrawBuffer.isEmpty()) ||
-								 m_touchMode == TouchMode::Drawing)) {
+		if(isTouchDrawEnabled() && ((m_touchMode == TouchMode::Unknown &&
+									 !m_touchDrawBuffer.isEmpty()) ||
+									m_touchMode == TouchMode::Drawing)) {
 			DP_EVENT_LOG(
 				"touch_draw_%s pendown=%d touching=%d type=%d device=%s "
 				"points=%s timestamp=%llu",

src/desktop/scene/canvasview.h

@@ -62,8 +62,9 @@ class CanvasView final : public QGraphicsView {
 	}
 
 	bool isTabletEnabled() const { return m_enableTablet; }
-	bool isTouchScrollEnabled() const { return m_enableTouchScroll; }
-	bool isTouchDrawEnabled() const { return m_enableTouchDraw; }
+	bool isTouchDrawEnabled() const;
+	bool isTouchPanEnabled() const;
+	bool isTouchDrawOrPanEnabled() const;
 
 	canvas::Point mapToCanvas(
 		long long timeMsec, const QPoint &point, qreal pressure, qreal xtilt,
@@ -90,8 +91,7 @@ class CanvasView final : public QGraphicsView {
 	void setTabletEnabled(bool enable) { m_enableTablet = enable; }
 
 	//! Enable/disable touch gestures
-	void setTouchScroll(bool scroll) { m_enableTouchScroll = scroll; }
-	void setTouchDraw(bool draw) { m_enableTouchDraw = draw; }
+	void setOneFingerTouchAction(int oneFingerTouchAction);
 	void setTouchPinch(bool pinch) { m_enableTouchPinch = pinch; }
 	void setTouchTwist(bool twist) { m_enableTouchTwist = twist; }
 	void setTouchUseGestureEvents(bool touchUseGestureEvents);
@@ -270,6 +270,7 @@ private slots:
 
 	void startTabletEventTimer()
 	{
+		m_anyTabletEventsReceived = true;
 		if(m_tabletEventTimerDelay > 0) {
 			m_tabletEventTimer.setRemainingTime(m_tabletEventTimerDelay);
 		}
@@ -431,10 +432,11 @@ private slots:
 	bool m_pointertracking;
 	bool m_pixelgrid;
 
-	bool m_enableTouchScroll, m_enableTouchDraw;
 	bool m_enableTouchPinch, m_enableTouchTwist;
 	bool m_useGestureEvents;
 	bool m_touching, m_touchRotating;
+	bool m_anyTabletEventsReceived;
+	int m_oneFingerTouchAction;
 	TouchMode m_touchMode;
 	QVector<QPair<long long, QPointF>> m_touchDrawBuffer;
 	qreal m_touchStartZoom, m_touchStartRotate;

src/desktop/scene/scenewrapper.cpp

@@ -47,7 +47,7 @@ bool SceneWrapper::isTabletEnabled() const
 
 bool SceneWrapper::isTouchScrollEnabled() const
 {
-	return m_view->isTouchScrollEnabled();
+	return m_view->isTouchPanEnabled();
 }
 
 bool SceneWrapper::isTouchDrawEnabled() const

src/desktop/settings.cpp

@@ -99,6 +99,42 @@ namespace newCanvasBackColor {
 	}
 }
 
+namespace oneFingerTouch {
+	QVariant get(const SettingMeta &meta, QSettings &settings)
+	{
+		if (findKey(settings, meta.baseKey, meta.version)) {
+			bool ok;
+			int value = any::get(meta, settings).toInt(&ok);
+			if(ok) {
+				switch(value) {
+				case int(OneFingerTouchAction::Nothing):
+				case int(OneFingerTouchAction::Draw):
+				case int(OneFingerTouchAction::Pan):
+				case int(OneFingerTouchAction::Guess):
+					return value;
+				default:
+					break;
+				}
+			}
+			return int(ONE_FINGER_TOUCH_DEFAULT);
+		}
+
+		std::optional<libclient::settings::FoundKey> touchDrawKey = findKey(
+			settings, "settings/input/touchdraw", SettingMeta::Version::V0);
+		if(touchDrawKey.has_value() && settings.value(touchDrawKey->key).toBool()) {
+			return int(OneFingerTouchAction::Draw);
+		}
+
+		std::optional<libclient::settings::FoundKey> touchScrollKey = findKey(
+			settings, "settings/input/touchscroll", SettingMeta::Version::V0);
+		if(touchScrollKey.has_value() && settings.value(touchScrollKey->key).toBool()) {
+			return int(OneFingerTouchAction::Pan);
+		}
+
+		return int(ONE_FINGER_TOUCH_DEFAULT);
+	}
+}
+
 namespace tabletDriver {
 	QVariant get(const SettingMeta &meta, QSettings &settings)
 	{

src/desktop/settings.h

@@ -51,6 +51,14 @@ enum class KineticScrollGesture : int {
 };
 Q_ENUM_NS(KineticScrollGesture)
 
+enum class OneFingerTouchAction : int {
+	Nothing,
+	Pan,
+	Draw,
+	Guess,
+};
+Q_ENUM_NS(OneFingerTouchAction)
+
 enum class ThemePalette : int {
 	System,
 	Light,

src/desktop/settings_table.h

@@ -28,6 +28,14 @@
 #	endif
 #endif
 
+#ifndef ONE_FINGER_TOUCH_DEFAULT
+#	if defined(Q_OS_ANDROID) || defined(__EMSCRIPTEN__)
+#		define ONE_FINGER_TOUCH_DEFAULT desktop::settings::OneFingerTouchAction::Guess
+#	else
+#		define ONE_FINGER_TOUCH_DEFAULT desktop::settings::OneFingerTouchAction::Pan
+#	endif
+#endif
+
 #ifndef OVERRIDE_FONT_SIZE_DEFAULT
 #	if defined(Q_OS_ANDROID) || defined(__EMSCRIPTEN__)
 #		define OVERRIDE_FONT_SIZE_DEFAULT true
@@ -171,8 +179,8 @@ SETTING(notifSoundLogin           , NotifSoundLogin           , "notifications/l
 SETTING(notifSoundLogout          , NotifSoundLogout          , "notifications/logout"                  , true)
 SETTING(notifSoundPrivateChat     , NotifSoundPrivateChat     , "notifications/privatechat"             , true)
 SETTING(notifSoundUnlock          , NotifSoundUnlock          , "notifications/unlock"                  , true)
-SETTING(oneFingerDraw             , OneFingerDraw             , "settings/input/touchdraw"              , false)
-SETTING(oneFingerScroll           , OneFingerScroll           , "settings/input/touchscroll"            , true)
+SETTING_GETSET(oneFingerTouch     , OneFingerTouch            , "settings/input/onefinertouch"          , int(ONE_FINGER_TOUCH_DEFAULT)
+	, &oneFingerTouch::get, &any::set)
 SETTING(tabletPressTimerDelay     , TabletPressTimerDelay     , "settings/input/tabletpresstimerdelay"  , 500)
 SETTING(touchGestures             , TouchGestures             , "settings/input/touchgestures"          , false)
 SETTING(onionSkinsFrameCount      , OnionSkinsFrameCount      , "onionskins/framecount"                 , 8)